Would Humans Born On Mars Grow Taller Than Earthlings?

If we ever manage to overcome the fertility and sex troubles of space , we'll probably be popping out little humanoid children on other planets. But our little tykes might not stay little for very long.

On Earth we experience the steady hand of gravity at 1 g force constantly throughout our lifetimes. On other planets in our solar system, that's just not possible. Researchers are working on ways to make artificial gravity possible in order to make long flights easier on human bodies. According to NASA, most astronauts grow about 2 inches while they're in space because the reduced gravity causes the fluid between vertebrae to expand. They lose the height within 10 days of returning to Earth's crushing gravity. Because of the growth, NASA uses space suits that have extra room to accommodate the additional height.

(You also grow taller when you sleep : As you lie in bed, gravity pushes you down and elongates your spine enough so that when you wake up you're usually about half an inch taller than the previous night.)

Grab those Martians for your basketball team Mars settlement-proponent Robert Zubrin has theorized that children born on other planets with lower gravity, like Mars, which has just one-third of Earth's gravitational pull would in fact grow taller by a few inches than they would have on Earth. While genes inherited from their parents wouldn't change, the spine could elongate more than on Earth. Fortunately, Martian kids born in a low-g environment wouldn't suffer from the muscle mass and bone problems that long-flight astronauts do.

Unfortunately, the biggest possible problem with your Galactic Globetrotters may surface if low-gravity-born humans tried to return to Earth. They'd experience three times their home gravity and could suffer serious bone problems. For example, one NASA scientist, Al Globus, gives an example of someone who weighs 160 pounds. If I went to a 3g planet, the equivalent of moving from Mars to Earth, I would weigh almost 500 pounds and would have great difficulty getting out of bed, Globus said. For children raised on the moon or Mars, attending college on Earth will be out of the question.

Katherine Harmon

Katherine Harmon Courage is an award-winning freelance journalist and contributing editor for Scientific American. She has written for The New York Times, Wired, Gourmet, Popular Science, Prevention, and others, covering everything from breaking science news to features about food. She is the author of the book Octopus! The Most Mysterious Creature In the Sea, and her work was featured in The Best American Science and Nature Writing 2013. She graduated from Vassar College with an honor's degree in English and earned a master's degree from the University of Missouri's School of Journalism. She lives in Colorado, where she also competes in marathons and triathlons. Follow her on Twitter @KHCourage, and read more on her website www.KatherineCourage.com.